Noise suppressor for burner

ABSTRACT

The invention provides a sound absorbing construction for industrial burners. The sound produced by the burner is forced to move in a labyrinth path lined with sound absorbing material.

United States Patent 11 1 1111 3,907,489

Santisi Sept. 23, 1975 [54] NOISE SUPPRESSOR FOR BURNER 3,684,424 8/1972Zink et al. 431/114 [75] Inventor: Harry C. Santisi, Dresher, Pa.

[73] Assignee: Selas Corporation of America, primary Examiner EdwardFavors Dresher, Pa.

[22] Filed: Oct. 3, 1974 [21] Appl. No.: 511,938

[57] ABSTRACT 52 us. c1. 431/114 51 1111. c1. rzsc 7/04 The memo"provldes a Sound absorbmg construc' 58 Field 61 Search 431/114, 167, 166tion for industrial burners- The Sound Produced by the burner is forcedto move in a labyrinth path lined with [56] References Cited soundabsorbing material.

UNITED STATES PATENTS 2,964,121 12/1960 Zink, Jr. et a]. 431/114 X 3Claims, 2 Drawing Figures j r////////'////////z OI'IIIIIIIIIIIIII USPatent Sept. 23,1975 3,907,489

FIG.|

NOISE SUPPRESSOR FOR BURNER BACKGROUND OF INVENTION r The presentinvention relates to industrial gas burners and more particularly tosilencers to be used with inspirating gas burners. t

Inspirator type burners employ a gas orifice inserted close to thethroat of a venturi. Gas'is discharged at pressures as high as 30 p.s.i.through the orifice to create a low pressure area in the throat of theventuri for entraining the combustion air. Actual burner pressuresproduced by this type of mixing are quitelow which means that large openareas are required-for the combustion air in order to avoidexcessive-pressure drop. With such large areas, the noise generated bythe high pressure, high velocitygas can readily escape from the furnace.It is not unusual for the, high pressure jet to produce noise levelsabove 100 decibels.

This type of noise can be quite objectionable and is believed, afterprolonged exposure to levels above 90 dicibels, to result in some lossof hearing. Consequently, many furnace users are now specifyingequipmerit with low noise levels.

In addition, regulations under the Occupational Safety and Health Actrequire noise levels lower than those normally produced by some burners,particularly for prolonged exposure to the noise.

SUMMARY OF THE INVENTION The present invention includes baffle means oftibrous sound absorbing material arranged around the fuel and air supplyend of a burner in such a manner that a labyrinth passage is defined forthe air supply. The structure holding the fibrous material is soarranged that there is provided adequate cross-sectional area to permituninterrupted entrainment of atmospheric air to the burner.

It is an object of the invention to provide a sound absorbing unit to beused with an industrial gas burner.

It is a further object of the invention to provide structure withlabyrinth paths for air being supplied to a burner thereby to dampen outburner noise.

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,however, its advantages and specific objects attained with its use,reference should be had to the accompanying drawings and descriptivematter in which I have illustrated and described a preferred embodimentof the invention.

IN THE DRAWINGS FIG. 1 is a sectional view of the silencer showing itmounted on a burner, and

FIG. 2 is a view taken on line 22 of FIG. 1.

DETAILED DESCRIPTION Referring to the drawing, there is shown a portionof a furnace wall 1 having a metal backing plate 2. Both the wall andthe plate are provided with an opening through which a burner isinserted for heating the furnace. As shown, the burner comprises aventuri 3 having its discharge end extending through the wall openinginto the furnace interior. The venturi is provided with a radially andaxially extending flange 4 by means of which it is fastened in positionon the furnace wall. A secondary air shutter 5 is slideable on theventuri and is held in adjusted position by a thumb screw 6. Thisshutter is of a size to close the opening in the furnace wall as shown.Axial adjustment of this shutter along the venturi regulates the amountof secondary air that can flow through the wall opening and around theburner into the furnace.

The left or inlet end of venturi 3 is provided with the usual bell 7that has a spider 8 supporting concentrically a sleeve 9. An orifice, orspud as it is usually called, 11 is threaded into sleeve 9. Fuel gasunder pressure is supplied to the burner by a pipe 12 to be dischargedthrough the spud. As the fuel gas is discharged through orifice 11 itwill aspirate primary air in the bell 7 and supply a fuel air mixture tothe furnace. The amount of primary air aspirated is controlled by ashutter 13 attached to a sleeve 14 that is slideably received on pipe12. The shutter is held in its adjusted position by a thumb screw 15.The escaping fuel gas produces a noise, varying with the pressure andthe gas composition, that can be quite loud and objectionable.

'Arsilencer to be used with the burner is mounted on the furnace wall bya pair of studs 16. The silencer includes a first part 17 that isattached to studs 16 by bolts 18. Part 17 is provided with a radialflange 19 to which is attached by a similar flange, a cup-shaped part 21which, along with part 17 forms a silencer casing. As best shown in FIG.2, the end face of part 17 is provided with a central opening 22 that ismoved over hell 7 when this part is being mounted on studs 16. The faceis also provided with a plurality of arcuate openings 23 through whichprimary air flows to the burner.

The interior surface of the cylindrical portion of parts 17 and 21 arelined with a thick layer 24 of sound absorbing material such asfiberglas. A similar layer 25 of fiberglas or the like is placed againstthe radially extending wall of part 21. The diameter of the casing willdepend upon the size of the burner with which it is used. As an example,a burner in which bell 7 is five inches in diameter would have a casingapproximately fourteen inches in diameter and the sound absorbingmaterial will be about two inches thick.

Additional sound absorbing material in the form of a sleeve 26 is heldin place by a strap 27 with the ends of the sleeve abutting against aflange on bell 7 and the end face of part 17. Thus, an annular passagefor air is formed between two bodies of sound absorbing material. Inaddition, shutter 13 is shown as being dishshaped and provided with adisc 28 of sound absorbing material immediately back of the primary airopening in bell 7.

It will be seen that the construction requires sound waves produced bythe jet of fuel gas exiting from spud 11 must move in a tortuous orlabyrinth path and against the flow of primary air before they aredissipated to the surroundings. The entire path of travel of the soundwaves is lined on both sides by heavy layers of sound absorbingmaterial. Thus, the sound waves are substantially reduced as they traveloutwardly from the burner. Any noise that might be produced by theinflowing primary air is also dampened as it moves toward bell 7. It isnoted that the passages provided for the air are large enough so thatthere is no real reduction of its pressure or velocity as it flows intothe burner.

'tage without a corresponding use of other features.

It will therefore be seen that the constru ctionof this inventionsubstantially encloses the noise producing gas flows in a soundabsorbing chamber therebytrapdeparting from the spirit andscope of theinvention set forth in the appended claims, and that in some'casescertain features of my invention may be 'used to advan 'What is claimedis:

1. In combination, a burner having a portion adapted to be inserted in afurnace wall and being provided with a venturi having an open bellspaced from said wall; a cylindrical casing having one end closed, meansto mount saidcasing surrounding and spaced from-said bell with theclosed end thereof facing the open end of the bell,,a; layer ofsoundabsorbing material lining the interiorlof said casing, a sleeve'of soundabsorbingmateri al mounted on; and surrounding said bell, the extebemade in the form of the apparatus disclosed without v passage.

rior of the sieeyeQand the interior of the casing lining forming anannular passage for primary air to the burner, and means to dischargegas under pressure into said bell thereby to aspirate air through saidannular 2. The combination of claim 1 in which said means fordischarging gas extends axially through the closed end of said casing, adamper for said bell slideable axially on said gas discharging means insaid casing, and a facingof sound absorbing material on the bell side ofsaid damper.

3. In combination, .a burner having a venturi with a bell, the end ofthe bell being open,'a sound absorbing 'bell-to provide an'annular airpassage between the interior of saidcasing and the exterior of saidsleeveQand niea'ns toi disc harge gas under pressure into said bellthereby aspirati'ng'air through said annular passage. xi

1. In combination, a burner having a portion adapted to Be inserted in afurnace wall and being provided with a venturi having an open bellspaced from said wall, a cylindrical casing having one end closed, meansto mount said casing surrounding and spaced from said bell with theclosed end thereof facing the open end of the bell, a layer of soundabsorbing material lining the interior of said casing, a sleeve of soundabsorbing material mounted on and surrounding said bell, the exterior ofthe sleeve and the interior of the casing lining forming an annularpassage for primary air to the burner, and means to discharge gas underpressure into said bell thereby to aspirate air through said annularpassage.
 2. The combination of claim 1 in which said means fordischarging gas extends axially through the closed end of said casing, adamper for said bell slideable axially on said gas discharging means insaid casing, and a facing of sound absorbing material on the bell sideof said damper.
 3. In combination, a burner having a venturi with abell, the end of the bell being open, a sound absorbing devicecomprising a cylindrical casing having one end closed, means to mountsaid casing in a position surrounding said bell with the closed endthereof facing the open end of the venturi bell, a layer of soundinsulating material on the interior surface of said casing, a sleeve ofsound insulating material surrounding said bell to provide an annularair passage between the interior of said casing and the exterior of saidsleeve, and means to discharge gas under pressure into said bell therebyaspirating air through said annular passage.